1. Field of the Invention
This invention relates to apparatus and methods for measuring and accumulating the customer consumption of a utility, for example water, gas or electricity, and in particular to such a system which is self-powered, requiring only an energy input from the utility meter, the output of which is being measured and stored, or the energy input from an interrogation unit.
2. State of the Prior Art
It has been a long-standing problem of utility companies dealing with the distribution of such utilities as water, gas or electricity, for example, to obtain an indication of the utility consumption by each of its customers, so that customers may be accurately billed for their consumption. It has been a typical practice for the utility company to forward an inquiry by post to the customer, requesting that the customer read out from a meter installed at his location or house, and recored by writing the current reading onto a card before returning the card to the utility company. Such a system is subject to errors in that the customer may deliberately falsify the reading and/or inaccurately record it. Alternatively, the utility company may employ "meter readers" to visit each customer location or home and take the reading, by visually observing the meter and recording in tabulated form a hand-written record of the utility consumption and the corresponding customer. Such a method is very time-consuming and thus costly, in that the meter reader must typically gain access to the interior of the customer's house, wherein the meter is located, and on many occasions will find the customer absent, thus requiring repeated returns to secure the necessary reading. In addition, such a visual and hand-written method of recording typically is very inaccurate in that the numbers making up the meter reading often are misread or inaccurately recorded.
An improvement over such methods of obtaining utility meter readings comprises a display or readout disposed remotely of the utility meter, typically in a position outside of the customer's home or place of business. Thus, the "meter reader" does not have to gain access to the interior of the customer's house or place of business to make the desired reading. Still, the reader must visually read the plurality of numbers displayed upon the remote readout or display, and record the numbers upon his log. As described above, such visual readout and recording by hand-written insertions is subject to a high degree of inaccuracy.
The assignee of this invention has previously developed a significant improvement to the aforedescribed prior art methods and apparatus for obtaining utility readings, known as the Tele-Tape Remote Readout System (TTR). In this system, the utility meter, illustratively a water meter, measures the flow of water to incrementally record upon a coupled, mechanical-type register, an indication of the amount of water consumed by the customer. In turn, an electrical signal is derived from the register upon application of a portable interrogation unit and is applied to a receptacle, typically located upon the exterior of the customer's home or place of business, whereby a portable interrogation unit carried by the meter reader to the customer's location, is coupled thereto to derive a readout signal indicative of the water consumption by the customer. More specifically, the interrogation unit takes the form of a portable device including a storage medium, typically a tape cassette of the Phillips type, upon which electrical signals are recorded indicative of the water consumption, as well as a customer identification number.
The problems associated with such a "TTR" system will become more apparent as a description of its details is made. The mechanical register associated with the water meter comprises a series of wheels, the positions of which indicate successive magnitudes, e.g. units, tens, hundreds, thousands, of the quantity of water consumed. For example, the water meter incrementally moves the register for each 100 or 1,000 gallons of water that the customer has consumed. An electrical signal is derived to indicate the position of each of the wheels and thus the water consumed, by a plurality of resistance ladders, one associated with each wheel. Selected connections are made through a plurality of switching diodes to a coupling receptacle disposed upon the exterior of the customer's home or place of business, whereby the utility reader may readily gain access to the mechanical register. In addition, a circuitboard or wiring matrix is disposed, illustratively within the external receptacle, that is so configured or wired to uniquely identify the customer.
In order to obtain a meter reading, the meter reader gains access to the remote receptacle by coupling a connector in the form of a gun through a removable face plate, whereby the interrogator gun including contacts, is coupled with contacts within the remote receptacle so that an electrical connection is made between the portable interrogation unit and the mechanical register associated with the utility meter. Upon insertion of the interrogating gun, the control logic associated with the portable interrogation unit, sequentially reads out or obtains an encoded readout signal from the resistance ladder associated with each of the wheels of the mechanical register, and a six-digit identification signal from the aforedescribed wiring matrix.
One of the significant problems associated with the TTR system is the price of manufacturing such a unit, especially when its cost is compared with the cost of large-scale, integrated (LSI) devices that are capable of performing similar functions. In particular, the mechanical encoder, including a plurality of wheels, resistance ladders and sets of contacts for interconnecting the encoding wheels and resistance ladders are relatively expensive to manufacture. In particular, the sets of contacts employed by the resistance ladder for determining the position of its encoding wheel would become corroded by moisture or contaminants in the atmosphere, unless rather expensive measures, typically in the form of coating with a noble metal such as silver or gold, are taken; otherwise, a contact resistance problem would occur such that the output signal derived from the encoding wheels would be inaccurate. Similar contact problems also are encountered in the interconnection made between the interrogating gun and the set of contacts within the external receptacle, and these mating sets of contacts must be protected by suitable coatings that will not be corroded by moisture or contaminants within the atmosphere. A further problem resides in the relatively expensive nature of encoding each utility meter with a unique identification number identifying the customer. The wiring matrix utilized in the "TTR" system typically is hand-wired to provide the unique six-digit customer identification number. Further, such a manufacturing process requires that the matrix be manufactured at the factory and then subsequently installed at the customer's location.
If modern LSI components are to be employed to provide a storage of the quantity of the utility consumed by the customer, as well as his unique identification number, several problems are encountered. First, it is contemplated to use power supplied from the line voltage available at the customer's location. If the line voltage should fail for any of a variety of reasons, the signals stored within conventional LSI memories indicative of the utility consumed as well as the customer's identification number, may well be lost. Further, if such a system were to depend upon the line voltage for energization, it would be necessary to provide a suitable connection between the line and the utility meter. In any event, the energization as well as the continued storage of the amount of the utility consumed and the customer's identification number, must be secure.